CN103237418A - Judging method for warping of PCB (Printed Circuit Board) - Google Patents

Abstract

The invention discloses a judging method for the warping of a PCB (Printed Circuit Board). The judging method comprises the following steps of obtaining information of a processing size, a stacking structure drawing and a surface treatment process of the PCB according to the production type of the PCB; by using a prepreg in each layer in a stacked structure as an analysis cutting point, sequentially cutting from a prepreg in the first layer to a prepreg in the last layer, using the prepreg which is used as a cutting point as an analysis unit, using the upper side part of the prepreg as an analysis unit, and using the lower side part of the prepreg as an analysis unit; calculating the curvature of each cutting unit according to obtained information of elasticity modulus and thermal expansion coefficient of each analysis unit, and calculating an algebraic sum; and calculating a warping degree of the PCB according to the total curvature, and outputting a result, wherein the numerical value of the warping degree includes a positive value and a negative value, the positive value represents that the PCB is warped towards a CS layer, and the negative value represents that the PCB is warped towards an SS layer.

Description

The determination methods of printed circuit slab warping

Technical field

The present invention relates to the printed circuit board technology field, particularly relate to a kind of determination methods of printed circuit slab warping.

Background technology

Along with the progress of mounting technology, proposed harsher requirement for the evenness of printed circuit board, mount requirement in order to satisfy electronics, angularity has been put into whether one of qualified test item of printed board.Because the angularity design factor is many, the mechanism complexity, the angularity problem becomes the puzzlement of printed circuit board manufacturer, and for addressing this problem, the method for taking at present has: the first, rule of thumb the regular warpage that provides different structure is accepted standard; The second, receive the high printed board of standard for the difficult control of warpage or warpage, strengthen the production management and control, as prolong lamination cold pressing pressurize that baking is handled after time, the boring and shipment before carry out the hot pressing leveling.The defective of above method is to design end can not be predicted its project organization before production warpage degree, need scrap benefit in case the process warpage of manufacturing exceeds standard throws, the warpage issues that causes for structural design need be manufactured experimently first plate and can be determined the warpage scope and improve countermeasure, prolonged the process-cycle, production cost also can increase.

Summary of the invention

Based on this, at the problems referred to above, the present invention proposes a kind of determination methods that can predict the printed board warpage of printed circuit board angularity before production.

Technical scheme of the present invention is: a kind of determination methods of printed circuit slab warping may further comprise the steps:

According to the production model of printed circuit board, obtain the information of its processing dimension, folded composition and process of surface treatment;

With each layer prepreg in the laminated construction as analyzing cutpoint, cut apart successively to last one deck prepreg from the ground floor prepreg, will be as this layer prepreg of cut-point as an analytic unit, the prepreg upper portion is as an analytic unit, and lower portion is as an analytic unit;

Modulus of elasticity and thermal coefficient of expansion information according to each analytic unit that obtains calculate the curvature of each cutting unit and ask algebraical sum;

Calculate the angularity of printed circuit board and export the result according to total curvature, the numerical value of angularity comprise on the occasion of and negative value, stick up the layer to CS on the occasion of representing printed circuit board, negative value represents printed circuit board and sticks up the layer to SS.

In a preferred embodiment, further comprising the steps of: as when the numerical value of the angularity that calculates exceeds default numerical value, to provide optimization folded structure according to warp direction.

In a preferred embodiment, to the modulus of elasticity that solidifies summit temperature, calculate as follows by the modulus of heat treatment process base material from room temperature for the test different materials:

$E_{\mathrm{xb}}=\frac{E_{T1}+E_{T2}}{2}$

Wherein, E _XbBe the average elasticity modulus of base material, ET1 is the modulus of elasticity under the base material room temperature, E _T2Solidify the modulus of elasticity of summit temperature for base material.

In a preferred embodiment, prepreg is made up of glass fabric and resin, and the modulus of heat treatment process prepreg is calculated as follows:

$E_{\mathrm{pp}}=\frac{E_g+E_{\∞}}{2}$

$E_z=\frac{\mathrm{\Σ}\left(E_{\mathrm{xb}}{h}_{\mathrm{xb}}\right)+\mathrm{\Σ}\left(E_{\mathrm{pp}}{h}_{\mathrm{pp}}\right)+\mathrm{\Σ}\left(E_{\mathrm{cu}}{h}_{\mathrm{cu}}\right)}{\mathrm{\Σ}{h}_{\mathrm{xb}}+\mathrm{\Σ}{h}_{\mathrm{pp}}+\mathrm{\Σ}{h}_{\mathrm{cu}}}$

Wherein, E _PpBe the average elasticity modulus of semi-solid preparation, E _gModulus of elasticity during for the gel of semi-solid preparation, E _∞Modulus of elasticity when solidifying fully for prepreg, E _zBe total mixing modulus of elasticity of base material, prepreg and Copper Foil, h _XbBe the thickness of base material, h _PpBe the theoretic throat of prepreg, h _CuBe copper thickness.

In a preferred embodiment, the processing formula of thermal coefficient of expansion CTE is:

$\mathrm{CTE}=\frac{\mathrm{\Σ}{\mathrm{CTE}}_{\mathrm{xb}}{h}_{\mathrm{xb}}+\mathrm{\Σ}{\mathrm{CTE}}_{\mathrm{pp}}{h}_{\mathrm{pp}}}{\mathrm{\Σ}{h}_{\mathrm{xb}}+\mathrm{\Σ}{h}_{\mathrm{pp}}}$

Wherein, CTE _XbBe the CTE of base material, CTE _PpCTE when solidifying fully for prepreg, h _XbBe the thickness of base material, h _PpTheoretic throat for prepreg.

The invention has the beneficial effects as follows: can predict the warpage of printed board before production, the serious printed board of warpage to doping can provide the optimization that improves warpage laminated construction, improves product qualified rate, shortens process-cycle and processing cost.

Description of drawings

Fig. 1 is the flow chart of the described determination methods of the embodiment of the invention;

Fig. 2 is a structural analysis figure of printed circuit board in the embodiment of the invention;

Fig. 3 is another structural analysis figure of printed circuit board in the embodiment of the invention.

Embodiment

Below in conjunction with accompanying drawing embodiments of the invention are elaborated.

Embodiment:

As shown in Figure 1, a kind of determination methods of printed circuit slab warping may further comprise the steps:

Step S101 according to the production model of printed circuit board, obtains the information of its processing dimension, folded composition and process of surface treatment;

Step S102, with each layer prepreg in the laminated construction as analyzing cutpoint, cut apart successively to last one deck prepreg from the ground floor prepreg, will be as this layer prepreg of cut-point as an analytic unit, the prepreg upper portion is as an analytic unit, and lower portion is as an analytic unit;

Step S103, modulus of elasticity and thermal coefficient of expansion information according to each analytic unit that obtains calculate the curvature of each cutting unit and ask algebraical sum;

Step S104 calculates the angularity of printed circuit board and exports the result according to total curvature, the numerical value of angularity comprise on the occasion of and negative value, stick up the layer to CS on the occasion of representing printed circuit board, negative value represents printed circuit board and sticks up the layer to SS.

Step S105 when the numerical value of the angularity that calculates exceeds default numerical value, provides optimization folded structure according to warp direction.

In the present embodiment, to the modulus of elasticity that solidifies summit temperature, calculate as follows by the modulus of heat treatment process base material from room temperature for the test different materials:

$E_{\mathrm{xb}}=\frac{E_{T1}+E_{T2}}{2}$

Wherein, E _XbBe the average elasticity modulus of base material, E _T1Be the modulus of elasticity under the base material room temperature, E _T2Solidify the modulus of elasticity of summit temperature for base material.

In the present embodiment, prepreg is made up of glass fabric and resin, and the modulus of heat treatment process prepreg is calculated as follows:

$E_{\mathrm{pp}}=\frac{E_g+E_{\∞}}{2}$

$E_z=\frac{\mathrm{\Σ}\left(E_{\mathrm{xb}}{h}_{\mathrm{xb}}\right)+\mathrm{\Σ}\left(E_{\mathrm{pp}}{h}_{\mathrm{pp}}\right)+\mathrm{\Σ}\left(E_{\mathrm{cu}}{h}_{\mathrm{cu}}\right)}{\mathrm{\Σ}{h}_{\mathrm{xb}}+\mathrm{\Σ}{h}_{\mathrm{pp}}+\mathrm{\Σ}{h}_{\mathrm{cu}}}$

Wherein, E _PpBe the average elasticity modulus of semi-solid preparation, E _gModulus of elasticity during for the gel of semi-solid preparation, E _∞Modulus of elasticity when solidifying fully for prepreg, E _zBe total mixing modulus of elasticity of base material, prepreg and Copper Foil, h _XbBe the thickness of base material, h _PpBe the theoretic throat of prepreg, h _CuBe copper thickness.

In the present embodiment, the processing formula of thermal coefficient of expansion CTE is:

$\mathrm{CTE}=\frac{\mathrm{\Σ}{\mathrm{CTE}}_{\mathrm{xb}}{h}_{\mathrm{xb}}+\mathrm{\Σ}{\mathrm{CTE}}_{\mathrm{pp}}{h}_{\mathrm{pp}}}{\mathrm{\Σ}{h}_{\mathrm{xb}}+\mathrm{\Σ}{h}_{\mathrm{pp}}}$

Wherein, CTE _XbBe the CTE of base material, CTE _PpCTE when solidifying fully for prepreg, h _XbBe the thickness of base material, h _PpTheoretic throat for prepreg.

As shown in Figure 2, label 2 is first layer of prepreg, label 4 is second layer of prepreg, always has 2 layers of prepreg and need cut apart 2 times, when first layer of prepreg 2 is cut apart, label 1 is the upside analytic unit, label 3,4,5 is jointly as the downside analytic unit, information extraction from 3 analytic units then,, sheet material type thick as central layer thickness, residual copper rate, copper, prepreg model, size, obtain modulus of elasticity and thermal coefficient of expansion, calculate the curvature 1 that forms.

When second layer of prepreg 4 is cut apart, as shown in Figure 3, label 1,2,3 is the upside analytic unit, label 5 is the downside analytic unit, information extraction from 3 analytic units then,, sheet material type thick as central layer thickness, residual copper rate, copper, prepreg model, size are obtained modulus of elasticity and thermal coefficient of expansion, calculate the curvature 2 that forms.

Be example with 6 layers of printed circuit board plate 6a49403xa3 below, be illustrated:

1. design before producing

(1) input production model 6a49403xa3, obtain data from ERP automatically: processing dimension 18*16inch, finished size 200mm*160mm, surface treatment is turmeric, folded structure situation is as follows:

Laminated information is as follows:

(2) by analysis program to calculate maximum angularity be-0.756%, warp direction is the SS face, is 0.75% and the client accepts maximum warpage, and the risk that exceeds standard is arranged.According to warp direction, the laminated construction situation of optimization is as follows:

Laminated information is as follows:

(3) the maximum angularity of the laminated construction of program calculation optimization is-0.459% by analysis.

2. after structure is determined routinely production method produce complete production process such as following table:

3. warpage test: the client accepts standard: maximum angularity≤0.75%, this batch tested qualification rate 100% according to IPC-TM-650.

The above embodiment has only expressed the specific embodiment of the present invention, and it describes comparatively concrete and detailed, but can not therefore be interpreted as the restriction to claim of the present invention.Should be pointed out that for the person of ordinary skill of the art without departing from the inventive concept of the premise, can also make some distortion and improvement, these all belong to protection scope of the present invention.

Claims (5)

1. the determination methods of a printed circuit slab warping is characterized in that, may further comprise the steps:

According to the production model of printed circuit board, obtain the information of its processing dimension, folded composition and process of surface treatment;

With each layer prepreg in the laminated construction as analyzing cutpoint, cut apart successively to last one deck prepreg from the ground floor prepreg, will be as this layer prepreg of cut-point as an analytic unit, the prepreg upper portion is as an analytic unit, and lower portion is as an analytic unit;

Modulus of elasticity and thermal coefficient of expansion information according to each analytic unit that obtains calculate the curvature of each cutting unit and ask algebraical sum;

Calculate the angularity of printed circuit board and export the result according to total curvature, the numerical value of angularity comprise on the occasion of and negative value, stick up the layer to CS on the occasion of representing printed circuit board, negative value represents printed circuit board and sticks up the layer to SS.

2. the determination methods of printed circuit slab warping according to claim 1 is characterized in that, and is further comprising the steps of:

When the numerical value of the angularity that calculates exceeds default numerical value, provide optimization folded structure according to warp direction.

3. the determination methods of printed circuit slab warping according to claim 1 and 2 is characterized in that, to the modulus of elasticity that solidifies summit temperature, calculate as follows by the modulus of heat treatment process base material from room temperature for the test different materials:

$E_{\mathrm{xb}}=\frac{E_{T1}+E_{T2}}{2}$

Wherein, E _XbBe the average elasticity modulus of base material, E _T1Be the modulus of elasticity under the base material room temperature, E _T2Solidify the modulus of elasticity of summit temperature for base material.

4. the determination methods of printed circuit slab warping according to claim 1 and 2 is characterized in that, prepreg is made up of glass fabric and resin, and the modulus of heat treatment process prepreg is calculated as follows:

$E_{\mathrm{pp}}=\frac{E_g+E_{\∞}}{2}$

$E_z=\frac{\mathrm{\Σ}\left(E_{\mathrm{xb}}{h}_{\mathrm{xb}}\right)+\mathrm{\Σ}\left(E_{\mathrm{pp}}{h}_{\mathrm{pp}}\right)+\mathrm{\Σ}\left(E_{\mathrm{cu}}{h}_{\mathrm{cu}}\right)}{\mathrm{\Σ}{h}_{\mathrm{xb}}+\mathrm{\Σ}{h}_{\mathrm{pp}}+\mathrm{\Σ}{h}_{\mathrm{cu}}}$

Wherein, E _PpBe the average elasticity modulus of semi-solid preparation, E _gModulus of elasticity during for the gel of semi-solid preparation, E _∞Modulus of elasticity when solidifying fully for prepreg, E _zBe total mixing modulus of elasticity of base material, prepreg and Copper Foil, h _XbBe the thickness of base material, h _PpBe the theoretic throat of prepreg, h _CuBe copper thickness.

5. the determination methods of printed circuit slab warping according to claim 1 and 2 is characterized in that, the processing formula of thermal coefficient of expansion CTE is:

$\mathrm{CTE}=\frac{\mathrm{\Σ}{\mathrm{CTE}}_{\mathrm{xb}}{h}_{\mathrm{xb}}+\mathrm{\Σ}{\mathrm{CTE}}_{\mathrm{pp}}{h}_{\mathrm{pp}}}{\mathrm{\Σ}{h}_{\mathrm{xb}}+\mathrm{\Σ}{h}_{\mathrm{pp}}}$

Wherein, CTE _XbBe the CTE of base material, CTE _PpCTE when solidifying fully for prepreg, h _XbBe the thickness of base material, h _PpTheoretic throat for prepreg.

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